Technical Description of OBD-II Trouble Code
The circuit for controlling the Secondary Air Injection System A is experiencing low voltage.
What is the meaning of P2257?
P2257 is a generic powertrain code that applies to many OBD-II vehicles (1996-newer). This includes vehicles from Mazda, BMW, Ford, Dodge, Saab, Range Rover, Jaguar, and others. While it is a generic code, the specific repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
When a P2257 code is stored, it indicates that the powertrain control module (PCM) has detected low voltage on the control circuit designated as “A” for the secondary air injection system. To determine the location of the “A” circuit for your specific application, refer to a vehicle-specific repair manual.
The secondary air injection system consists of a belt-driven or electric pump that injects ambient air into the engine exhaust system to reduce emissions. Heat-resistant, silicon-based hoses supply the pump with cool ambient air, which is filtered before entering the air filter housing or a remote inlet housing designed for the secondary air injection system.
Ambient air is pumped into the exhaust system through high-temperature silicon and steel lines connected to ports in the exhaust downpipes. One-way check valves are installed in each exhaust hose to prevent condensation from entering the pump and causing malfunctions. These valves often fail.
The PCM controls the operation of the secondary air injection pump based on factors such as engine temperature, engine RPM, and throttle position. These factors can vary depending on the vehicle manufacturer.
If the PCM detects insufficient voltage on the control circuit “A” of the secondary air injection system, it will store a P2257 code and illuminate the malfunction indicator lamp (MIL). The MIL may require multiple ignition cycles with a failure to illuminate.
Components of the secondary air injection system:
What is the severity of this DTC?
Conditions that contribute to a stored P2257 code could result in damage to the secondary air injection pump. Therefore, this code should be considered severe.
What are some of the symptoms of the code?
Symptoms of a P2257 trouble code may include:
What are some of the common causes of the code?
Causes of this code may include:
What are some troubleshooting steps for P2257?
To accurately diagnose a P2257 code, you will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information.
It may save time to search for technical service bulletins (TSB) that match the stored code, vehicle information (year, make, model, and engine), and exhibited symptoms. This information can be found in your vehicle information source. If you find the appropriate TSB, it may provide a quick solution to your diagnosis.
After connecting the scanner to the vehicle diagnostic port and retrieving all stored codes and freeze frame data, write down the information in case the code is intermittent. Then, clear the codes and test drive the vehicle until one of two things happens: the code is restored or the PCM enters readiness mode.
If the PCM enters readiness mode at this point, diagnosing the code may be more difficult because it is intermittent. The condition that caused the P2257 code to be stored may need to worsen before an accurate diagnosis can be made. If the code is restored, continue with the diagnosis.
You can obtain connector face views, connector pinout charts, component locator charts, wiring diagrams, and diagnostic flow charts specific to the code and vehicle in question from your source of vehicle information.
Perform a visual inspection of the related wiring and connectors. Repair or replace any wiring that is cut, burned, or damaged.
Use the DVOM to test the control voltage of the secondary air injection system at the appropriate connector pin. If no voltage is detected, check the system fuses and replace any blown or defective fuses as necessary.
If voltage is detected, test the corresponding circuit at the PCM connector. If no voltage is detected there, suspect an open circuit between the sensor in question and the PCM. If voltage is found there, suspect a defective PCM or PCM programming error.
